Microwave klystron construction



Nov. 18, 1958 G. c. DALMAN MICROWAVE KLYSTRON CONSTRUCTION INVENTOR 6 /54 CD44 MAN 2 Sheets-Sheet 1 TTORNEY Filed Aug. 1, 1956 Nov. 18, 1958 G. c. DALMAN MICROWAVE KLYSTRON CONSTRUCTION 2 Sheets-Sheet 2 Filed Aug. 1, 1956 INVENTOR G754 CDAL MAN BY I ATTORNEY -simple and inexpensive. cies the'energy .must be removed from theresonator by -means of a waveguide. Because of the relatively large United States Patent 2,861,213 IMICROWAVEZKIJYSTRONJCONSTRUCTION Rand Corporation, a corporation of Delaware Application August 1, 1956, Serial No.'60 1,417

16 Claims. (Cl."3155.22)

Thisinvention'relates to electron'dis'charge devices,- and more particularlyto:output'coupling structures for klystrons. I

--In many klystrons microwave energy is developed'inan evacuated cavity resonator. At-lower microwave frequencies this energy :may be-utilized by transmitting it 'frornthe resonatorto a-load througha coaxialline. The coaxial lines and the methods of attaching :them to the resonator in vacuum-sealed relationship-are mechanically At higher microwave frequencross-sectional area and the rigidity f the waveguide structure prior art'klystrons employingwaveguide output assemblies have been mechanicallycomplex and'expensive to' fabricate.

It is therefore the principal-object of this'inventionsto provide animproved coupling structure for.an-electron discharge device.

his a further object of this inventiontoprovideanimproved waveguide coupling-structure for areflex-klystron.

' 'lt'is'afurther objectof this inventionto provide animproved waveguide output structure connected in vacuum sealed relation to-the cavityresonator of a reflex klystron.

"It is a further object of this invention to provide an improved klystrondevice that is-relatively inexpensive and simple to fabricate and'is readilyadapted to mass production techniques.

cavity resonatorhave acommon wall, an aperture in'the common wall serving to transmit energy-from the resonator to the intermediate coupler. An additional aperture in the intermediate couplenprovides for energy.transfer-to the output=waveguide. .A'reflexklystron employing this typeof outputcoupling-is simple and inexpensive to "fabricate and employs fewer par-ts than prior art klystrons having waveguide'output assemblies.

'Thisinvention will be described-with reference to the following drawings, wherein: 1

'Fig. lis a longitudinal-section.drawingof a reflex klystron tube employingithe structureof thisinvention; ":Fig. 2 is a sectional view of the'klystron alongtheline 2-'2 of Fig. '1.

Fig. 3:is:a. sectional yiew of thezklystron along the line Fig. 4 is an exploded view showingthe manner of :as-

*sembly'of' portions. of the-klystron of Fig. 1.

The reflex klystron of'Figs. 1,. 2, 3, 4 comprises a plurality of subassemblies within a, cylindricalshell indicated "ice ' generally as 10. Five major subassemblies areseparately GislixC. Dalman, I Iuntington, N."Y,, assignor to'Sperry fabricated and thenjoined together to form the klystron. These subassembliesinclude the'lower shell, the cathode, the upper shell, the reflector, and the tunersubassemblies.

The lower shell subassembly comprises a lower shell "portion 11, whichmay consist of copper-plated colddrawn baseflange 12 and an endwall 13. End wall "13 is formed "with a depression-having a Cylindrical side wall 14 and a circular bottomwall 15. Bottom wall 15 is provided with an apertured conical reentrant-portion' 16. A- mesh grid 17 is welded to the top edge of reentrant portion 16. A -'lead-wire 18-is'inserte d-in aninsulatingbushing 19, which in turn i-s fitted intoa hole in end-wall 13.

The cathode subassembly comprises a cathodebutton "-ZOQacyIind-ricaL heat shield 21 welded'at its upper edge -to-cathode button' Zt), and a thin cylindrical foil member 22- aflixed to the edge of the heat shield near cathode button'2tl. Foil member 22'may be'formed of thin Kovar, titanium or tantalum to prevent the conduction of heat away 'from cathode button 20. Cathode button 20 is suit ably coated-with an-electron-emissive-material. A focus heater 24 isdisposedinside heat shield 21-andservesto elevate the temperature-of cathode button 20. The combinationof cathode button 20,-heat shield 21, and'focus electrode 23 comprises an electron gun. A mica washer 25, provided with holes 26 to aid evacuation, abuts a 'flang'e 27 on focuselectrode 23. A threadedcylinder 28 engages the threaded outer-portionof focus electrode'23, 'forcing rriicawasher'ZS against flange '27. Focus electrode 23 and mica'washer ZS are adjusted for concentricity in a jig structure when threaded cylinder ZS-is tightened against -washer '25.

An annular anode member 30 -is held against bottom wall 15 by mica washer '25. A gun alignment cylinder 31 *has a small flange 32 at its lower edge. Alignment cylinder 31 has substantially the same inner diameter as the outer diameter of cylindrical wall 14 and is provided with slits 33 parallel to the axis of the klystron in order that it may be'forced over the outer surface of cylindrical wall 14. Three spring members 34, each aflixed at one end thereof to gun alignment cylinder 31, urge said cylinder upward against cylindrical wall 14, whereby the electron gun isheld in concentric alignment with the aperture in reentrant portion 16.

Theupper shell subassembly comprises'an upper shell portion 40, which may consist-of cold drawn steel formed into hollow cylindrical form and having a lowerlip 41 and anupper flange 4-2. A rectangular output aperture i43'is provided in-thecylindrical surface of upper shell portion- 40. A rectangular waveguide section 44 is brazed externally in vacuum-sealed relation to upper shell portion-4and-adaptedto surround aperture '43. A waveguide'fia-nge 45 is brazed to the outer end of waveguide -section 44. A diaphragm retaining ring 46 is brazed to the'inner; surface of upper shell portion 40 immediately above aperture '43. The entire upper. shell subassembly posed opposite the apertured portion of diaphragm 50 and is welded between diaphragm 50 and lip 49. A reflector electrode 52 is supported opposite grid 51 and within sleeve 43 by a mica washer 53.

A reflector lead 54 is connected to reflector electrode 52 and projects from sleeve 48 through a slot 55 in sleeve 48. An insulator 56 in slot 55 prevents electrical contact between reflector lead 54 and sleeve 48. An inner screw member 57 having an enlarged base portion 58 is held within sleeve 48, by projections 59 of sleeve 48 engaging a groove 60 of base portion 58. Base portion 58 in turn holds mica washer 53 and consequently re-'t flector electrode 52 rigidly within sleeve 48. The reflector subassembly is aflixed to end wall 13 by welding thereto the outer peripheral edges of diaphragm 50. Diaphragm 50, cylindrical wall 14, and bottom wall with its reentrant portion 16 define the walls of a cavity resonator 61. Reflector lead 54 is welded to the end of lead wire 18.

A flexible vacuum diaphragm 63 is brazed in a vacuum-tight manner at its inner periphery to sleeve 48 and at its outer periphery to diaphragm retaining ring 46.

A tuner stop member 65 is adjusted on inner screw member 57, so that at the maximum desirable inward penetration of screw member 57, stop member 65 abuts against flange 42. The tuner subassembly comprises an outer screw member 66, a spring 67 and a tuner cap 63.

Outer screw member 66 is threadedly engaged with inner screw member 57 and an inner threaded portion of toner cap 68. The combination of tuner cap 68, outer screw member 66 and inner screw member 57 comprises a differential screw tuner. flange 42 thereby fixing the tuner subassembly with respect to shell 10.

After most of the tube has been assembled in the order Tuner cap 68 is soldered to heretofore described, a mica vacuum window 70 is hand- Also aflixed to header 72 are trons through apertured anode member 30 and across' the interelectrode gap defined by grids 17 and 51. The electron stream is reflected by reflector electrode 52 and returns through the interelectrode gap. In a manner well known in the art, electromagnetic oscillations are set up in cavity resonator 61 at the resonant frequency thereof. By adjustment of tuner screw 66, which raises or lowers screw member 57, the spacing between grids 17 and 51 is varied, and, thus, the resonant frequency of cavity 61 is controlled. Base portion 58 of inner screw member 57 provides a conductive short across the end of reflector sleeve 48 thereby preventing any leakage of electromagnetic energy past reflector electrode 52.

In accordance with the principles of this invention, novel means is provided for removing the electromagnetic energy from cavity resonator 61 and transferring it to waveguide section 44 where it may be delivered to a load.

Flexible diaphragm 50 includes an additional aperture 78 outside sleeve 48. Aperture 78 is shown as being crescent in shape, but it is within the spirit of this invention for it to be any suitable form. Vacuum diaphragm 63, flexito flexible diaphragm 50 so that the length of the resulting coaxial line section is less than one-half wavelength at the highest operating frequency desired. This prevents the coaxial line section from acting as a resonant cavity of low Q, and reducing the output power. Energy is transferred from intermediate coupler 80, through output aperture 43, into waveguide section 44, where it may be delivered to a load.

While the invention has been described in its preferred embodiment, it is to be understood that the words which have been used are words of description rather than of limitation and that changes within the purview of the appended claims may be made without departing from the true scope and spirit of the invention in its broader aspects.

What is claimed is:

1. An output coupling structure for a reflex klystron comprising a conductive enclosing vessel having a flexible wall portion, a cavity resonator fixedly mounted within said vessel and having a flexible wall portion, said resonator flexible wall portion being provided with a first aperture and being disposed opposite said vessel flexible wall portion, a rigid hollow conductive tube afiixed at each end thereof to a respective one of said flexible wall portions, the end of said tube affixed to said resonator flexible wall portion being adapted to surround said first aperture, an electron reflecting electrode insulatingly supported within said tube, said resonator flexible wall portion being further provided with a second aperture outside said tube, whereby said second aperture serves to transfer electromagnetic energy from said cavity resonator to an intermediate coupler, said enclosing vessel, said enclosing vessel flexible wall portion, said tube, and said resonator flexible wall portion defining in part the walls of said intermediate coupler, and further coupling means for removing electromagnetic energy from said intermediate coupler.

2. An output coupling structure for a reflex klystron comprising a. conductive cylindrical shell, a flexible wall extending across the interior of said shell in vacuum sealed relation to the inner surface thereof, a hollow annular cavity resonator coaxially disposed within said shell, one wall of said resonator being provided with a flexible portion, said flexible portion being provided with a central circular first aperture and being disposed opposite said flexible wall, an annular disc extending between the outer circular surface of said resonator and the inner surface of said shell and rigidly supporting said resonator within said shell, a rigid hollow conductive tube aflixed at one end thereof to said flexible wall and at the other end thereof to said flexible portion, the end of said tube afl'ixed to said flexible portion being of greater inside diameter than the diameter of said first aperture and being adapted to surround said first aperture, and an electron reflecting electrode insulatingly supported within said tube, said one resonator wall being further provided with a second aperture outside said tube, whereby said second aperture serves to transfer electromagnetic energy from said cavity resonator to an intermediate coupler, said shell, said flexible wall, said one resonator wall, said annular disc, and said tube defining in part the walls of said intermediate coupler, said cylindrical shell being provided with a third aperture between said flexible wall and said annular disc whereby electromagnetic energy may be removed from said intermediate coupler.

3. An output coupling structure, as in claim 2, further including a conductive member, said member being adapted to enclose said tube at said one end thereof, whereby leakage of electromagnetic energy through said 'tube is prevented.

4. A reflex klystron comprising a conductive enclosing vessel having a flexible wall portion, a cavity resonator mounted within said vessel and having a pair of opposed Walls, one of said resonator walls being provided with a --flexible :portion, said flexible portion? beingzprovidedlwith I a T-first aperture and being dispose-d rippositessaid zvessel flexible wall portion, the other of said resonator 'walls being provided with a second aperture aligned with said first aperture, an electron gun aligned-with 'said first and second apertures and oppositesaid other resonator wall for projecting an electron stream through said first and end of said tube affixed to said resonator flexible wall portion being adapted to surround said first aperture, an electron reflecting electrode insulatingly supported within said tube, said resonator flexible wall portion being provided with a third aperture outside said tube, whereby said third aperture serves to transfer electromagnetic energy from said cavity resonator to an intermediate coupler, said enclosing vessel, said enclosing vessel flexible wall portion, said tube, said one resonator wall, and said resonator flexible wall portion defining in part the walls of said intermediate coupler, and further coupling means for removing electromagnetic energy from said intermediate coupler.

5. A reflex klystron as in claim 4, further including tuning means mounted on said enclosing vessel and connected to said tube for varying the longitudinal position thereof and thereby changing the resonant frequency of the cavity resonator.

6. A reflex klystron as in claim 4, further including a conductive member, said member being adapted to enclose said tube at the other end thereof, whereby leakage of electromagnetic energy through said tube is prevented, a portion of said conductive member extending beyond said tube and having screw threads thereon, and tuning means mounted on said enclosing vessel and engaging said conductive member screw threads for varying the longitudinal position of said tube.

7. An output coupling structure for an electron discharge tube comprising a cylindrical conductive shell, a first flexible conductive wall extending across the interior of said shell in vacuum sealed relation to the inner surface thereof, a second flexible conductive wall extending across said shell opposite said first wall, a rigid rod affixed at each end thereof to a respective one of said flexible walls, said second wall being provided with an aperture, whereby said aperture serves to transfer electromagnetic energy into the hollow structure bounded by said shell and said first and second walls, and further coupling means for removing electromagnetic energy from said hollow structure. a

8. An output coupling structure as set forth in claim 7, wherein said further coupling means comprises a rectangular aperture through said cylindrical conductive shell, and a section of rectangular wave guide having an end coupled to said aperture.

9. In a velocity modulation device a subassembly comprising a hollow conductive member having an integral end wall, said end wall being provided with a depression having a cylindrical side wall and a circular bottom wall, said bottom wall being provided with a circular aperture concentrically located therein, an alignment cylinder having an internal diameter substantially equal to the external diameter of said cylindrical wall, an electron gun rigidly connected to said alignment cylinder and coaxial therewith, the electron emitting surface of said gun facing said aperture, and spring means fixed at one end with respect to said hollow member and connected at the other end :its routemperiphery' at!) .:said::endi"wall, .wherebyzalncavity :resonatortis -.definedby' .said depression wallsrand:saidxeiricularzflexiblemember.

.11. In ..:a'-. velocity modulation idevice aii-subassembly comprising av hollow iconductive :member "having 'an: in-

I 4 'tegralend wall; said end wall being provided with -ade- 'pressionl 'having a. cylindrical s'ide' wall' and a circular bottom wall, saidbottom wan being-provided -with'- a ir-r r culariaperture *concentrically'flocated thereinyanfalignment c'ylinder, andan 'ele'ctromgumrigidly' "connected" to comprising a conductive cylindrical shell, a hollow annular cavity resonator concentrically disposed within said shell, one wall of said resonator being provided with a v flexible portion, said flexible portion being provided with a central circular first aperture, said resonator being rigidly supported within said shell by an annular disc extending between the outer circular surface of said resonator and the inner surface of said shell, a rigid hollow conductive tube aflixed at one end thereof to said flexible portion, said tube end being of greater inside diameter to said alignment cylinder whereby one end of said alignthan the diameter of said first aperture and being adapted to surround said first aperture, a conductive flexible annulusjextending between the outer surface of said tube and the inner surface of said shell in vacuum-sealed relation thereto, and an electron reflecting electrode insulatingly supported within said tube, said one resonator wall being further provided with a second aperture outside said r tube, whereby said second aperture serves to transfer electromagnetic energy from said cavity resonator to an intermediate coupler, said shell, said flexible annulus, said one resonator wall, said annular disc, and said tube defining in part the walls of said intermediate coupler, said cylindrical shell being provided with a third aperture between said flexible annulus and said annular disc, whereby electromagnetic energy may be removed from said intermediate coupler.

13. An output coupling structure as in claim 12, further including a section of rectangular waveguide aflixed to the outer surface of said shell in vacuum-sealed relation thereto and adapted to surround said third aperture, and a dielectric window member extending across said waveguide section and sealed to the walls thereof.

14. A coupling structure as in claim 12 wherein the distance between said flexible portion and said flexible annulus as measured along the axis of said cylindrical shell is less than one-half wavelength at the maximum frequency of the electromagnetic energy to be transferred through said intermediate coupler.

15. An output coupling structure as in claim 12 wherein said hollow conductive tube is provided with an aperture in the wall thereof between said flexible wall and said flexible portion, and wherein said annular disc is provided with an aperture, and further comprising a conductive lead connected to said reflecting electrode, said conductive .lead extending through said tube aperture, said intermediate coupler, and said annular disc aperture.

16. A re'flex klystron subassembly comprising a hollow conductive member having an integral end wall, said end wall being provided with a depression having a side wall and a bottom wall, a flexible member provided with an aperture and affixed to said end wall to cover said depression, a first hollow conductive tube afiixed to said flexible member and surrounding the flexible member tending through said firsttube aperture and said end wan intermediate coupler, and further coupling means for re- :aperture, afsecond hollow conductive-tube disposed-"co- -moving electromagnetic energy from said intermediate axially about said first tube, one end of said second tube coupler. being atfixed to said end wall in vacuum-sealed relation thereto, .a flexible conductive diaphragm extending be- 5: References Cited in the file offihis .tween the outer surfac'e ;0f..said first tube and theiinner surface of said second tube atla point jalong said vfirst UNITED STATES PATENTS tube opposite said first tube aperture'fronl saidtflexible 2,5( 8,46 f Laifertyd May l6, 1950 member, said first and secondtubes, ,said flexiblemember, U 2,566,584 Shepherd Sept. 4, 1951 said end wall, and said flexible diaphragm definingan '10 2,653,273 Sloan Sept. 22, 1953 

